The BBC has seen evidence he set up the new British group known as the Sonnenkrieg Division.

Mr Dymock, who is originally from Bath and whose father is a dentistry professor, has been studying at university in Wales.

A key propagandist – responsible for designing extremist material – is said to be Oskar Koczorowski from west London, who is only 17 years old.

He did not respond to a request for comment.

Pseudonyms

A BBC researcher has been able to obtain hundreds of messages sent by several extremists over several months on an online gaming server.

The messages show neo-Nazis from Europe and the US – hiding behind pseudonyms – engaging in racism and misogyny, glorifying violence and cruelty, and discussing the production of propaganda.

Warning: One of their violent images is displayed below.

The chat logs include senior members of the Atomwaffen Division, a nihilistic American organisation that encourages terrorism and says civilisation needs to be smashed in order to build a national socialist state.

Image caption

Neo-Nazis from Europe and the US hide behind pseudonyms in the online chats

The group promotes a dystopian ideology it calls "universal order" which lionises Adolf Hitler, the murderous cult leader Charles Manson, and the veteran neo-Nazi ideologue James Mason, who provides regular diatribes for a website run by Atomwaffen members.

Atomwaffen – the word means atomic weapons in German – has been linked to five murders and its co-founder was jailed earlier this year for explosives offences.

Online propaganda videos show Atomwaffen members engaging in firearms training and calling for a "race war now".

Messages from the gaming server include correspondence about the creation of the Sonnenkrieg Division.

"Blitzy" described Sonnenkrieg as "full on Universal Order" and "atomwaffen with less guns".

He also discussed his plans to travel to the US to meet Atomwaffen members in person.

In one exchange, he stated "kill all police officers" and said they should be "raped to death".

The BBC has obtained evidence that "Blitzy" is Mr Dymock, and that he and Mr Koczorowski, who uses a separate pseudonym, both placed Sonnenkrieg propaganda into the chats.

'A disease'

Violent images posted by the group on social media state "fill your heart with hate" and glorify the Norwegian terrorist and mass murderer Anders Breivik.

One image suggests that Prince Harry should be shot for marrying someone of mixed race and exclaims "see ya later race traitor".

Image caption

The image of Prince Harry carries the Sonnenkrieg Division branding

A further image, showing a female hanging from a noose, states that white women who date non-white men should be killed.

Mr Koczorowski posted images of himself wearing an Atomwaffen top near Parliament and a video of a British flag being burnt.

It is thought Sonnenkrieg has no more than 10-15 members in the UK and some European countries.

The parents of American teenager Blaze Bernstein, allegedly murdered by an Atomwaffen member in what is being treated as a hate crime, told the BBC that people in the UK should be wary of spin-offs of the group.

Image caption

The killing of Blaze Bernstein is being treated as a hate crime

Jeanne Pepper Bernstein, whose son was allegedly killed because he was gay and Jewish, said the "group is a disease and the only way to eradicate it is to figure out where it is and root it out".

Blaze's father Gideon said: "If it can happen to us it can happen anywhere in the world."

'University studies'

Other private messages show some neo-Nazis claiming they have encouraged young women to engage in acts of self-harm along with pictures of the mutilation and criticism of the women concerned.

It is understood that Mr Dymock has been questioned by police over alleged sexual offences against a teenage girl.

Images, allegedly shared by Mr Dymock with his associates and later placed online, show a swastika and runic symbols cut into a girl's naked body and – in another image – Mr Dymock appears to brandish a book by James Mason in the air as she lies on the floor.

The bed seen in the images is consistent with the background in a picture posted by "Blitzy" and another of Mr Dymock himself.

It is understood that both Mr Dymock and Mr Koczorowski were previously involved with the neo-Nazi group System Resistance Network, which can be linked to acts of racist vandalism in as many as 10 UK cities.

The BBC has been told that Mr Koczorowski was a pre-ban member of National Action, which became the first extreme-right organisation to be outlawed in the UK since the war when it was proscribed under terrorism legislation in December 2016.

The BBC approached both men setting out our findings and seeking comment.

Mr Dymock said through his lawyer that all our allegations were "wholly incorrect", that he was not a member of any organisation mentioned and any interest he did have was "associated with his university studies".

Mr Koczorowski came to the door of his London home wearing a hooded top emblazoned with the Atomwaffen Division logo. He did not respond to our allegations.